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AD - Anomalous Dispersion lens optics -
faster than light transmission. Conventional optical glass has very even dispersion for different wavelengths or colors. Most people are familiar with using a prism to split sunlight into a rainbow of colors, and many will recall that the colors are fairly evenly distributed across the width of the rainbow. AD glass doesn't spread the colors evenly. Instead, AD glass speads the colors at each end of the rainbow by very little compared to the colors in the middle of the rainbow. AD glass is a special type of optical glass which isn't cheap. Optical engineers use AD optics to control chromatic aberration in the deep blue and deep red portions of the color spectrum. This greatly reduces the dreaded color fringing for deep red and deep blue-violet colors, and greatly reduces lateral color. AD lens elements are particularly useful for minimizing chromatic aberration and lateral color in very wide angle to telephoto zoom lenses. |
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AD-Hybrid Aspherical. The use of LD and AD glass permits Tamron lenses to provide unparalleled optical quality while eliminating chromatic aberrations that can denigrate image contrast and sharpness. |
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AF - Auto Focus - All Tamron AF lenses feature fixed mounts for autofocus camera bodies rather than using the Adaptall-2 mount system. Note that some "AF" lenses were also made available in manual focus Adaptall-2 mount versions. |
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AF/MF Switchover Mechanism. One-touch AF/MF Switchover mechanisms (for Canon and Nikon only)
The models for Nikon and Canon cameras are equipped with AF/MF switchover mechanisms to allow one-touch switchover from AF mode to MF mode or vice versa electronically and mechanically by simply sliding the button. (Sony and Pentax systems require AF/MF switchover operation on both the camera and lens.)
Since the lens uses an IF (internal focusing) system, the focusing ring does not rotate during focusing, which ensures good holding balance at all times. In the MF mode, focusing is performed as easily and comfortably as with an MF lens. Since the overall length of the lens does not change due to zooming or focusing, it offers excellent operability and holding balance.
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Aspherical -
The
lens curved surface does not conform to the shape
of a sphere. An aspheric element is often called
an aspherical lens.
The asphere's more complex surface profile can eliminate
spherical aberration and reduce other
optical aberrations compared to a simple lens. A single aspheric lens can often replace a much more complex multi-lens system. The resulting device is smaller and lighter, and possibly cheaper than the multi-lens design. Aspheric elements are used in the design of multi-element wide-angle and fast
normal lenses to reduce aberrations.
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Built-In Motor for Nikon
Cameras. The updated versions now incorporates motor built-in to the lens itself, which gives this lens the capability to auto focus with all Nikon DSLR cameras (including the D40. D40x,
D60, D3000 and the D5000). In addition, as a result, focusing will be quieter and more responsive. |
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CF - Continuous Focus - The lens has the ability to continuously focus from infinity to macro mode. Some CF zoom lenses had this CF ability regardless of the set focal length, while other CF zoom lenses featured internal cams which would automatically zoom the lens towards a specific zoom setting as the focus ring was turned. This latter feature was referred to as the Minimum Object Distance (M.O.D.) Selector System. The M.O.D. feature was certainly much more convenient than having to press a "macro" button, as found on many similar competing lenses, in order to go into macro mode. Needless to say, M.O.D. increased the cost of a Tamron lens due to the extra internal focus/zoom coupling mechanisms. But once you used a Tamron CF lens which featured the M.O.D. Selector System, you were hooked due to the extraordinary convenience of the Tamron design. The CF designation has now been discontinued by Tamron, but older CF lenses were simply marked with the letters "CF MACRO" somewhere on the lens barrel (usually above the aperture ring). |
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DI - Digitally Integrated Design (to reduce
ghosting, flare, CA and peripheral light fall-off along
with improved resolution of the optical system to meet
the performance characteristics of digital SLR cameras
as well as film cameras). |
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Di-II Series Design
Lenses for DSLRs with APS-C sized sensors only The
design has been improved by adding a gold-colored band
between the focus and zoom rings to enhance the
appearance and make it stand out as a Di-II lens. The
rubber patterns of the zoom and focus control rings have
been improved at the same time to compliment the digital
camera design style and to p |
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FEC (Filter Effect Control)
Features the new FEC (Filter Effect Control) function that enhances operational ease of
polarizing filter use. The new Filter Effect Control is designed to rotate the filter to the desired position while the hood is attached. This is accomplished by turning the FEC ring that in turn rotates the portion of the filter mount where the filter is mounted.
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Internal Focusing
Internal focusing lens (also known as IF) is a
photographic lens design in which focus is shifted by moving the inner lens group or groups only, without any rotation or shifting of the front lens element. This makes it easy to use, for example, a screwed-in
polarizing filter or a petal shaped lens hood. During
macro photography, using an internal focus lens reduces the risk of the front of the lens accidentally hitting the subject during focusing as the front element does not move. |
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LD-Hybrid Aspherical. Lenses with LAH optics feature Tamron's proprietary low dispersion (LD) aspherical hybrid lens optics. LAH lenses utilize one or more LD aspherical hybrid lens elements within their optical designs. A LAH lens element is composed of a low dispersion (LD) element onto which a resin based aspherical surface is bonded. Apparently only Tamron has developed the proprietary technology to accomplish this feat since LD elements are fragile by nature.
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LD Low Dispersion lens elements (to reduce chromatic aberration for sharper images) Aspherical - contains aspherical elements (compensates for spherical aberration and distortion, making for better performance with fewer elements (and As a result allowing for smaller, lighter lenses)
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Tamron macro lens series
Tamron designated lenses as "Macro" lenses only if the lens
is capable of achieving considerably closer focusing compared to many similar lenses, or if the lens featured either a macro button or some other form of specific mechanism in order to get into macro mode. If the lens merely featured continuous focusing to a very short focus distance, then it appears that Tamron gave the lens a "Macro" designation only if the lens could achieve a macro reproduction ratio of 1:6 or better. Lenses with a macro feature are marked with the letters "MACRO" somewhere on the lens barrel. Lenses with a telephoto macro feature are marked with the letters "TELE MACRO" somewhere on the lens barrel. |
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SP - Super Performance specifications.
Tamron's "SP" designation stands for "Super Performance". In the past, Tamron's lenses received the SP designation for any of or a combination of the following reasons:
- Superior sharpness and contrast due to an advanced or unique optical design.
- Low dispersion element(s) for apochromatic or near apochromatic performance.
- Internal focusing (compared to similar lenses of the era).
- Superior macro performance (compared to similar lenses of the era).
- An exceptional zoom range compared to similar lenses.
- A larger maximum aperture compared to similar lenses.
Today, many lenses produced by Tamron and other manufactures feature low dispersion elements and internal focusing. It appears that Tamron currently reserves its SP designation for lenses which meet any or a combination of the following criteria:
- Superior sharpness and contrast due to an advanced or unique optical design.
- Superior macro performance compared to similar lenses.
- An exceptional zoom range compared to similar lenses.
- A larger maximum aperture compared to similar lenses.
Older Tamron SP lenses were simply marked with the letters "SP" somewhere on the lens barrel (usually above the aperture ring), and many SP lenses also had "TAMRON SP" marked on the front element retaining ring and/or on the included built-in or standard accessory lens hood. Today's modern Tamron SP lenses are distinctively marked with a thin gold ring about the top of the lens barrel.
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ULTRASONIC SILENT DRIVE. Tamron’s USD works with the high-frequency ultrasonic vibrations that are produced by a ring called a ‘stator’. Energy from the vibrations is used to rotate an attached metallic ring known as the ‘rotor’. Piezoelectric ceramic, an element that produces ultrasonic vibrations when voltage of a specific frequency is applied is arranged in a ring formation on the stator. This electrode configuration of piezoelectric ceramic causes two ultrasonic vibrations to occur in the stator.
By effectively combining these two ultrasonic vibrations, it is possible to convert the energy from the vibrations that produced simple motion into energy known as ‘deflective traveling waves’, which then moves around the circumference (rotation direction) of the ring.
With the USD, the friction between these deflective traveling waves created on the metallic surface of the stator and the surface of the rotor produce force, causing the rotor to rotate. The focusing ring lens, which is linked to the rotor, is thus moved, creating a fast and smooth auto-focus drive.
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VC - Vibration Compensation. Tamron’s
proprietary tri-axial Vibration Compensation (VC)
mechanism that minimizes the effects of handheld camera
shake. Tamron’s image stabilization mechanism, controls the effects of camera shake in three planes. VC provides more opportunities for sharp hand-held photography (up to 4-stops) at the slow shutter speeds needed when shooting in low-light conditions (e.g. night or indoor scenes) dramatically enhancing the user’s level of photographic freedom.
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EXTRA LOW DISPERSION. A sophisticated XLD (Extra Low Dispersion) lens element made from specialized high-grade glass that has lower dispersive properties than standard LD lenses (where refraction causes the dispersion of white light into spectral hues). The dispersive properties of the XLD lens are at a level similar to fluorite, and in combination with LD elements make for an optimal optical design that delivers best in class resolution with advanced axial chromatic and magnification aberration correction - major inhibitors of image quality enhancement. The result is a lens that delivers sharp contrast and better descriptive performance throughout the entire zoom range.
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XR Technology. Extra Refractive Index Glass (reduces lens size).
The first most important reason that the lens is so compact is the use of high refractive index glass. That is, XR glass. High refractive index glass bends light more than normal or lower refractive index glasses. Normally, glass material having a refractive index of more than 1.69 is called high refractive index glass. In the A03 optical system, glass material having a refractive index of more than 1.69 is used in the front group. In addition, refractive index of the whole optical system is enhanced. By using high refractive index glass in the front group, we could make the elements in the first group thinner, and reduce one element in the second group. This made the overall length of the whole optical system shorter.
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Zoom lock mechanism for convenience in carrying the outfit
Tamron's "ZL" designation stands for "Zoom-Lock" mechanism. Many of today's zoom lenses utilize two or more zoom cams and feature large front elements which also move when the lens is zoomed. In some zoom lens designs, it is simply unavoidable for the zoom setting not to creep when the lens is tilted up or down. Tamron neatly solved this problem by incorporating a zoom-lock mechanism which locks the zoom setting in place.
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